Metal shearing machine

ABSTRACT

Two shearing blades disposed along two lines which intersect each other are carried on the bottom edges of two adjacent walls of a four-sided ram structure. The ram is supported at four points whereby to provide greater stability. The workpiece is carried on the aligned top surfaces of a fixed bed and a movable carriage. The movable carriage is movable in a first direction. Finger grippers, joined by a connecting bar, are movable in slots along the top surface of the movable carriage in a second direction. Thus, the workpiece is moved in the first direction by movement of the movable carriage and in the second direction by movement of the finger grippers. The workpiece may be precisely and accurately positioned under the shearing blades making use of sensors in each of the finger grippers and a lateral sensors in each of the finger grippers and a lateral sensor at the end of the movable carriage. The drives for driving the movable carriage and the finger grippers are controlled by a processor which also receives feedback signals from the drives indicative of the distances moved by the movable carriage and the finger grippers.

This application is a division, of application Ser. No. 168,143, filedMar. 14, 1988, now U.S. Pat. No. 4,811,640.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a metal shearing machine which cuts a workpiecesimultaneously along two intersecting lines.

More specifically, the invention relates to such a machine whichprovides a novel movable carriage means for the workpiece which ensuresmore accurate alignment of the workpiece with the shearing blades andpermits the handling of heavier workpieces.

In addition, the invention relates to such a machine having an improvedsupport and actuating system for the blade carrying ram.

Further, the invention relates to such a machine which includes meansfor sensing and manipulating the position of the workpiece on thecarriage means whereby to more accurately align the workpiece with thecutting blades.

2. Description of Prior Art

Metal shearing machines which cut simultaneously along two intersectinglines are known in the prior art as illustrated in, for example, U.S.Pat. Nos. 3,691,887, Roch, Sept. 19, 1972, 3,821,914, Roch, Jul. 2,1974, and 3,877,332, and Roch, Apr. 15, 1975 (all of which are relatedpatents and have the same teachings and are henceforth referred to asthe Group I patents), U.S. Pat. Nos. 3,828,639, Roch, Aug. 13, 1974 and3,942,400, Roch, Mar. 9, 1976 (which are related patents and have thesame teachings and are henceforth referred to as the Group II patents),U.S. Pat. No. 3,874,260, Roch, Apr. 1, 1975, U.S. Pat. No. 4,297,927,Kuroda, Nov. 3, 1981 and U.S. Pat. No. 4,519,284, Hunter et al, May 28,1985.

The Group I patents teach a machine having a three point support systemfor the blade carrying ram. With such a support system, the size of theblade which can be accommodated is limited as, with larger blades,shearing stability decreases thereby increasing distortions in thesheared material. The workpiece in the Group I patents is carried byfingers 38 extending from carriage 36. Fingers 38 are movable in thecarriage 36 to move the workpiece 21 in the direction indicated by arrow22 in FIG. 4 of these patents, and carriage 36 is movable in thedirection transverse to the direction of arrow 22 to move the workpiecein the transverse direction. Because the fingers are carrying the fullweight of the workpiece, the size (weight) of workpiece which can behandled by the machines according to the Group I patents is limited.

The Group II patents also teach a machine having a three point ramsupport. A workpiece is mounted on a table top 16 (see FIG. 1) and isgripped by grippers in carriage 17.

U.S. Pat. No. 3,874,260 teaches a method and apparatus for removingfinal blanks sheared from a sheet. A conveyor, adjacent the intersectinglower blanks, is tipped downward to accommodate the downward movement ofthe upper shearing blades, to thereby receive the sheared blank andconvey it away from the blades. The problems dealt with by the presentapplication are not dealt with in the '260 patent.

U.S. Pat. No. 4,297,927 teaches an arrangement similar to thearrangement of the Group I patents above-described. Specifically,grippers 44 and 46 (see FIG. 1 of the patent) are mounted on a carriage42 for movement along the work table 40. A slider 41 (see FIG. 2) isalso mounted on the carriage for movement across the work table. Thiscomplicated arrangement is used for the purpose of precisely positioningthe workpiece. Once again, the full weight of the metal workpiece mustbe supported by the grippers 44 and 46.

U.S. Pat. No. 4,519,284 teaches a transverse gripper assembly 46 and alongitudinal gripper assembly 48 (see FIG. 1 of the patent). Theworkpiece is gripped by one gripper assembly at a time to move along theappropriate axis. Thus, if it is necessary to move the workpiecetransversely, it is gripped by the gripper assembly 46 (but not thegripper assembly 48). To be moved in the longitudinal direction, it isgripped by the gripper assembly 48 (but not the gripper assembly 46).Thus, once again, a complicated arrangement is needed for preciselypositioning the workpiece. Also, once again, the workpiece is supportedsolely by the grippers so that the size (weight) of workpiece which canbe manipulated by these machines is limited as in the Group I patent.

SUMMARY OF INVENTION

It is therefore an object of the invention to provide an improved metalshearing machine which cuts a workpiece simultaneously along twointersecting lines.

It is a more specific object of the invention to provide such a machinehaving an improved support and activating system for the blade carryingram thereof.

It is a further object of the invention to provide a machine of theabove nature which provides a novel movable carriage means for theworkpiece.

It is a still further object of the invention to provide a machine ofthe above nature which includes means for sensing and manipulating theposition of the workpiece on the movable carriage means.

In accordance with the invention there is provided a metal shearingmachine for cutting a workpiece simultaneously along two intersectinglines. The machine includes shearing means comprising two shearingblades disposed along two lines which intersect each other. A ram meanscarries the shearing means. Means are provided for supporting andactivating the ram means to thereby move the ram means and the shearingmeans upwardly and downwardly. A means for supporting and activatingsupports the ram means at four points thereof.

In accordance with a further embodiment of the invention there isprovided a metal shearing machine for cutting a workpiece simultaneouslyalong two intersecting lines and including shearing means comprising twoshearing blades disposed along two lines which intersect each other. Themachine includes a table means for movingly supporting the workpiece.The table means comprises a fixed bed having a top surface and a movablecarriage having a top surface, the top surface of the fixed bed beingaligned with the top surface of the movable carriage means. The movablecarriage means is movable in a first direction. A first slot in the topsurface of the movable carriage means extends in a second directiontransverse to the first direction, and a second slot in the top surfaceof the movable carriage means extending in the second direction parallelto the first slot. A first finger gripper is mounted in the first slotfor movement along the first slot and a second finger gripper is mountedin the second slot for movement along the second slot. A bar meansconnects the first and second finger grippers to form a gripperarrangement whereby the first and second finger grippers are movabletogether. Whereby, when a workpiece is gripped by the finger grippers,it is movable in one direction by movement of the movable carriage, andit is movable in a second direction by movement of the gripperarrangement.

Each finger gripper preferably includes an upper and a lower jaw, theupper jaw being pivotable relative to the lower jaw. A sensor in eachfinger gripper senses when the workpiece is disposed between the upperand lower jaws of each finger gripper.

The invention also relates to a method for precisely and accuratelyaligning a workpiece in a desired position under the shearing blades ofa metal shearing machine. The metal shearing machine includes a movablecarriage means for carrying the workpiece, the movable carriage meansbeing movable in a first direction by a first drive means. A gripperarrangement, comprising two spaced finger grippers connected by aconnecting bar, is movable in a second direction, transverse to thefirst direction, along the top surface of the movable carriage by asecond drive means. A processor provides actuating signals to the firstand second drive means and receives feedback signals from the first andsecond drive means indicative of the distance moved by the movablecarriage in the first direction and by the gripper arrangement in thesecond direction. Each finger gripper includes sensor means to sensewhen a workpiece is in the finger gripper, the output of the sensormeans being fed to the processor. Each finger gripper also includescontrol means for effecting gripping of the workpiece when the workpieceis in the finger gripper, the control means being actuatable by theprocessor. The movable carriage is movable along the tracks from one endto the other end of a track bed, and a lateral sensor is disposed at theone end of the track bed, the output of the lateral sensor being fed tothe processor. The method includes the steps of inputting the dimensionsof the workpiece, the dimensions of the desired position of theworkpiece under the shearing blades and the dimensions of the positionof the lateral sensor into the processor. The workpiece is laid on thetop surface of the movable carriage in a random position. The processorcauses the second drive means to move the gripper arrangement in thesecond direction until the sensor means of one finger gripper sensesthat the workpiece is in the one finger gripper. The processor continuesto cause the second drive means to drive the gripper arrangement in thesecond direction until the sensor means of the other finger grippersenses that the workpiece is in the other finger gripper. The processorthen ceases to cause the second drive means to drive the gripperarrangement and records the position of the gripper arrangement on thecessation of the second drive means. The processor also actuates thecontrol means of both finger grippers to grip the workpiece. Theprocessor then causes the first drive means to move the moveablecarriage towards the lateral sensor along the one direction until thelateral sensor senses the presence of the workpiece, whereupon theposition of the movable carriage in the one direction is available tothe processor. The processor ceases to cause the first drive means todrive the movable carriage, the workpiece now being in a start position.The processor, using the dimensions of the start position and thedesired position, calculates the number of units the carriage must bemoved in the first direction and the gripper arrangement must be movedin the second direction to place the workpiece in the desired position.The processor causes the first drive means to move the movable carriagethe calculated number of units in the first direction and the seconddrive means to move the calculated number of units in the seconddirection, whereupon, the workpiece will underlie the shearing blades inthe desired position.

BRIEF DESCRIPTION OF DRAWINGS

The invention will be better understood by an examination of thefollowing description, together with the accompanying drawings, inwhich:

FIG. 1 is a perspective view of the inventive machine;

FIG. 2 illustrates in greater detail the gripper arrangement of theinventive machine;

FIG. 3 illustrates, in section, further details of the inventivemachine;

FIG. 4 illustrative schematically the position of the lateral sensor;and

FIGS. 5A, 5B, 5C and 5D illustrate how the position of a workpiece issensed using the gripper sensors and the lateral sensor.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIG. 1, the machine, illustrated generally at 1, comprisesa table for movingly supporting a workpiece, the table comprising afixed bed 3 and a movable carriage 5. The top surfaces of the fixed bedand the movable carriage are aligned with each other, and the topsurfaces of both the fixed bed and the movable carriage include aplurality of roller means 4 so that a workpiece can more easily slideover the top surfaces.

Movable carriage 5 is movable along tracks 7 mounted on a track bed 8 sothat the movable carriage is movable in the X direction. Driver 10provides the drive for the moving the movable carriage 5. A gripperarrangement 9 is mounted for moving across the top surface of a movablecarriage 5 in the Y direction. The gripper arrangement comprises asupport bar 11 attached to gripper fingers 13 and 15. As can be seen,gripper finger 13 is mounted for movement in slot 17 in the top surfaceof 5 and along the Y direction, while gripper finger 15 is mounted formovement in slot 19, also in the top surface of movable carriage 5 andalso extending in the Y direction. Support bar 11 ensures that bothgripper fingers 13 and 15 move together and for the same distance.Driver 12 provides the drive for moving the gripper arrangement 9. Thegripper arrangement will be more fully described below.

Both drivers 10 and 12 are under the control of a processor 14 and alsoprovide feedback to the processor. Thus, processor 14 can cause driver10 to move movable carriage 5 an accurate and precise number of units inthe X direction, and the processor is aware of the number of unitsmovable carriage 5 has moved in the X direction. In the same way,processor 14 can control driver 12 to move gripper arrangement 9 anaccurate and precise number of units in the Y direction, and theprocessor 14 records the number of units moved by the gripperarrangement 9 in the Y direction.

The machine also includes a system, indicated generally at 21, forsupporting and actuating a ram 23. As can be seen, in a preferredembodiment, the ram comprises a four-walled structure, the walls beingat an angle to each other and joned to each other at the ends thereof.The ram supports a shearing arrangement comprising shearing blade 25 andshearing blade 26. As can be seen, blades 25 and 26 extend along twointersecting lines and are mounted on two adjacent walls of the ram 23.

The system 21 is mountable in the enclosure 27 but is shown out of theenclosure for ease of description. The relationship between parts of thesystem 21 and parts of the enclosure 27 is described below.

The system 21 comprises a piston and cylinder arrangement 29 having acylinder 31 whose free end 33 is attached to wall 35 of the enclosure byretainer 37. Holes 39 of the retainer and hole 41 of the free end of thecylinder are aligned and a rod, not shown, extends through the alignedholes whereby the system 21 is attached to the enclosure 27.

The free end of piston 43, of piston and cylinder arrangement 29, isconnected to elongated carrier means 45, which is in paralledarrangement with cylinder arrangement 29. A bell crank 47 is pivotallyconnected to one end of the elongated carrier 45, and a bell crank 49 ispivotally connected to the other end of elongated carrier 45. Axle 51extends transversely of and through bell crank 47 and is attached to thebell crank 47 so that axle 51 will rotate with the bell crank 47 whenthe bell crank 47 is pivoted. In a like manner, axle 53 extendstransversely of and through and is attached to bell crank 49 to rotatewhen bell crank 49 pivots.

Bell crank 63 is attached to one end of axle 51 and bell crank 65 isattached to the other end of axle 51 such that the bell cranks willpivot when the axle rotates. In a like manner, bell crank 67 isconnected to one end of axle 53 and bell crank 69 is connected to theother end of axle 53 to pivot with the rotation of the axle 53. The freeends of bell cranks 63, 65, 67 and 69 are pivotally connected torespective points of the ram 23 by lilnks 70. Accordingly, ram 23 isconnected to system 21 at four separate points. In the illustratedembodiment, the ram is a rectangular structure, and the bell cranks areconnected to points on the long walls of the rectangle.

System 21 is mounted in enclosure 27 such that one end of axle 51extends through opening 55 and the other end of axle 51 extends throughopening 57. The axle 51 is rotatable in the openings 55 and 57.

In a like manner, one end of axle 53 extends through opening 59 and theother end of axle 53 extends through opening 61. Again, the axle 53 isrotatable in the opening 59 and 61.

In operation, when piston 43 extends out of cylinder 31 in the directionof the arrow 71, bell cranks 47 and 49 will pivot in the direction ofarrow 73 causing axles 51 and 53 to rotate in the same direction. Therotation of axle 51, together with the forward movement of carrier means45, will cause the ends of bell cranks 63 and 65, connected to links 70,to pivot downwardly. In a like manner, the ends of bell cranks 67 and69, connected to links 70, will similarly pivot downwardly. This will,of course, cause the ram 23 to move downwardly in a shearing motion.

When piston 43 is retracted into cylinder 31 in the direction oppositeto the direction of arrow 71, bell cranks 47 and 49 will pivot in thedirection opposite to the direction of arrow 73. Axles 51 and 53 willrotate in the same direciton, and this rotation, together with thebackward movement of carrier means 45, causes the ends of bell cranks63, 65, 67 and 69, connected to links 70, to pivot upwardly and lift theram.

Thus, the system 21, inasmuch as it provides a four point support forthe ram 23, and because of its unique structure, provides an improvedsupport and actuating system which can handle longer shearing blades.

Turning now to FIG. 2, each gripper finger, 13 or 15, comprises an upperjaw 75 and a lower jaw 77. The upper jaw is pivotable relative to thelower jaw about the pivot point 78.

As shown in FIG. 2, and more clearly in FIG. 3, the top surface of thelower jaw is in alignment with the top surface of the fixed bed 3 andthe movable carriage 5. Accordingly, the bottom surface of a workpiece85 will lie smoothly on the aligned top surfaces of the movable carriage5, the fixed bed 3 and the lower jaw.

A piston and cylinder arrangement 79 is provided for pivoting the upperjaw relative to the lower jaw. The cylinder of the piston and cylinderarrangement 79 is fixed to, for example, a sidewall 82 by a strap 84.Thus, when the piston of the piston and cylinder arrangement 79 isretracted, it will pivot the upper jaw 75 upwardly relative to the lowerjaw 77, and when the piston of the piston and cylinder arrangement 79 isextended out of the cylinder, it will pivot thhe upper jaw 75 downwardlytowards the lower jaw 77. A pressure hose 81 controls the operation ofpiston and cylinder arrangement 79.

Each gripper finger also includes a sensor 83 which can comprise, forexample, a light sensitive transistor or a microswitch, and which sensesthe presence of the workpiece between the upper and lower jaws of thegripper finger. The output of each sensor is connected to processor 14via cable means 80.

Turning to FIG. 3, it can be seen that the machine includes a lowerblade 87. As is well known in the art, the lower blade is aligned withthe upper blade 25, and a transverse lower blade (not shown) is alignedwith upper blade 26. The space to the left of the blades is open sothat, when the upper blades pass the lower blades in a downward movementof the ram, the workpiece 85 is sheared along the intersecting lines ofthe blades.

Turning now to FIG. 4, a sensor 91, whose output is connected toprocessor 14, is disposed at the end 89 of the track bed 8. The sensor91, together with the sensors 83 of the gripper fingers 13 and 15, areused for determining an initial position of a workpiece 85 as isexplained with respect to FIGS. 5A to 5D.

As seen in FIG. 5A, a workpiece 85 may be disposed in any randomposition on the top surface of the movable carriage 5. The grippingfingers 13 and 15 are then moved in the direction of the workpiece. Themovement is caused by a drive 12 as is well known in the art, and theextent of movement is monitored and fed to a processor (not shown). Asseen in FIG. 5B, one of the finger grippers will first reach theworkpiece 85 (finger gripper 15 in FIG. 5B). The sensor of fingergripper 15 will provide information to processor 14 that the workpiece85 is now in the finger gripper 15. Finger grippers 13 and 15 willcontinue moving in the direction towards the workpiece 85, i.e., in thedirection of the arrow 93 in FIG. 5B.

As the finger grippers continue their movement, the right hand end ofthe workpiece, pushed by finger gripper 15, moves relative to the lefthand end, and finger grippr 13 approaches the left hand end of theworkpiece 85. Eventually, finger gripper 13 will reach the other end ofworkpiece 85 as shown in FIG. 5C. The sensor will provide thisinformation to processor 14 which will, in turn, provide control signalsto piston and cylinder arrangements 79 of finger grippers to causefinger grippeers 13 and 15 to grip the left and right hand edgesrespectively of workpiece 85. Processor 14 now has the information thatthe workpiece is now within the grips of both finger grippers so thatmovement of the finger grippers in the direction of arrow 93 need nolonger be continued.

Before the procedure had been started, the dimensions of the workpiecewould have been fed to the processor 14. The distance that fingergrippers 13 and 15 have moved in the Y direction has also been providedto processor 14 as above described, so that the Y position of all pointsof the workpiece can be calculated by, and is therefore known to,processor 14.

Movable carriage 5 is then moved in the X direction (the direction ofthe arrow 95) of FIG. 5D until sensor 91 senses that the edge of theworkpiece is adjacent the sensor. As the position of the sensor 91 inthe X direction would be provided to processor 14, the position of allpoints of the workpiece in both the X and the Y direction is known toprocessor 14.

The desired position of the workpiece under the shears 25 and 26 willalso have been fed into processor 14. It therefore becomes a simplematter for the processor 14 to calculate the number of units which themovable carriage must move in the X direction, in a direction oppositeto the arrow 95 of FIG. 5D, and in the Y direction in the direction ofarrow 93, to locate the workpiece in the desired position under theshears 25 and 26.

Because of the fact that a workpiece is supported by the aligned topsurfaces of the fixed bed 3, the movable carriage 5 and the bottom jaws77, the machine can support a workpiece of substantial weight withoutany bending or other distortion of the workpiece.

Because the sensors 83 and 89 will accurately determined the initialposition of the workpiece 85, and because processor 14 controls, withaccuracy and precision, the movement of both the movable carriage 5 andthe gripper arrangement 9, the workpiece 85 can subsequently beaccurately and precisely positioned under the shearing means foraccurate and precise production of a sheared blank.

Although a particular embodiment has been described, this was for thepurpose of illustrating, but not limiting, the invention. Variousmodifications, which will come readily to the mind of one skilled in theart, are within the scope of the invention as defined in the appendedclaims.

I claim:
 1. A metal shearing machine for cutting a workpiecesimultaneously along two intersecting lines, comprising:shearing meanscomprising two shearing blades disposed along two lines which intersecteach other; ram means for carrying said shearing means; means forsupporting and activating said ram means to thereby move said ram meansand said shearing means upwardly and downwardly, said means forsupporting and activating supporting said ram means at four pointsthereof; said ram means comprising a four-walled structure; adjacentones of said walls being at an angle to each other and being joined toeach other at the ends thereof; said shearing blades underlying twoadjacent walls of said ram means; said four points being on two opposingwalls of said rams means adjacent the ends thereof.
 2. A machine asdefined in claim 1 wherein each ram wall is at right angles to adjacentram walls.
 3. A machine as defined in claim 2 wherein said means forsupporting and actuating and said ram means are surrounded by afour-walled enclosure, each wall of said enclosure being parallel to arespective wall of said ram means.
 4. A machine as defined in claim 3wherein said means for supporting and actuating comprises:a piston andcylinder arrangement; the free end of the cylinder being attached to onewall of said enclosure; the free end of the piston being attached to anelongated carrier means extending parallel to said piston and cylinderarrangement; a first bell crank pivotally connected to, and extendingdownwardly from, one end of said elongated carrier; a second bell crankpivotally connected to, and extending downwardly from, the other end ofsaid elongated carrier; a first axle attached to and extendingtransversely of and through said first bell crank; a second axleattached to and extending transversely of and through said second bellcrank; a third bell crank attached to one end of said first axle topivot with said first axle when said first axle rotates; a fourth bellcrank attached to the other end of said first axle to pivot with saidfirst axle when said first axle rotates; a fifth bell crank attached toone end of said second axle to pivot with said second axle when saidsecond axle rotates; a sixth bell crank connected to the other end ofsaid second axle to pivot with said second axle when said second axlerotates; the free end of said third bell crank being pivotally connectedto a first point of said ram; the free end of said fourth bell crankbeing pivotally connected to a second point of said ram; the free end ofsaid fifth bell crank being pivotally connected to a third point of saidram; the free end of said sixth bell crank being pivotally connected toa fourth point of said ram; whereby, said ram is moved upwardly anddownwardly by the action of said piston in said piston and cylinderarrangement.
 5. A machine as defined in claim 4 wherein said first pointis adjacent one end of one of the long walls of said rectangle;saidsecond point is adjacent the other end of said one of said long walls ofsaid rectangle; said third point is adjacent one end of the other longwalls of said rectangle; and said fourth point is adjacent the other endof said other long wall of said rectangle.
 6. A machine as defined inclaim 5 and including table means for movingly supporting said workpiecewhereby to position said workpiece beneath said shearing means tothereby cut said workpiece along the intersecting lines of said shearingmeans.